problem with paper white DP75SD!

Hi all
I am Chris from Malta i am interested in modifying Kindle so i can read pdf files whenever i have manuals or other pdf books

i have tried to jb a paperwhite 2 but missed some step and cannot open as
it is stuck :

" this demonstration device is either missing content or is disconnected from
network
configure device "
pressing on screen and nothing happens

what thoughts please

Chris